Furnace construction



` Aug 25s A. J. FISHER f I FURNACE CONSTRUCTION Filed July 26, 1940 Patented Aug. 25, i942 UNITED- STATES PATENT OFFICE 2.2mm A i to Bethlehem Steel Company, a corporation ot Pennsylvania Application July 26, 1940, Serial No. 347,595

4 claims.

My invention relates to furnaces and particularly to heat treating furnaces.

An object of my invention is to provide a heat treating furnace that shall embody means tov insure uniform heating of a charge placed therein.

Another object of my invention is to provide a heat treating furnace that shall embody means to reduce the time of heating a charge placed therein.

A more specic object of my invention is to provide a heattreating furnace having a supporting base for the material to be treated -that shall permit an easy ow -of heated atmosphere beneath the material and at the same time shall permit the bottom section of the material to be heated at a fter rate than is possible in designs of the prior art.

Other objects and advantages of my invention will be understood from the specification and drawing in which: Y

Figure l is a transverse section through my improved furnace; and

Figure 2 is a fragmentary top plan view of the device which more particularly embodies my invention.

In the heat treating of material, be it of annular material, such as coils of wire or strip coils, or iiat material such as sheets of metal, it has been found 'diilicult to obtain a uniform, temperature extending vertically of the mass of material to be treated. This has been so because the base plate upon which the treated material rested has been either an extremely heavy plate which conducted the heat away from the bottom section of the material or it has been of refractory material which prevented heat from-reaching the bottom section of the material. I have overcome these difilculties by providing a supporting base comprising two elements, one element to permit easy circulation of heated gas beneath the other element, the other element to quickly conduct heat to the material being treated. L

Referring to the drawing more in detail, Il is a furnace structure which is provided with a refractory base II resting upon a metal plate lI2 means for facilitating its removal is provided in the lug 20.

Hollow radiant tubes 2l provide heat to the furnace; Ithey extend longitudinally of the furnace in three batteries as shown, one battery along each side wall and one along the center line of the furnace. In operation tubes 2I are lled with burning gas which heats them to a high temperature; they then transmit this heat to other parts of the furnace by radiation.

Upon refractory supporting member I5 rests a plurality of my novel base plates I6 each of which are roughly in the shape of a segment of a circle as shown in Figure 2 and are provided with a plurality of short upstanding lugs 22. Lugs ,22

,v are shown in plan in Figure 2 as being approxiwalls of the hood 25 and the hot material 24 be'- mately diamond-shaped, which shape I have found to be preferable to the even'dstribution of gases to all parts of the heating plate 23, but it should 'be understood that other patterns polygonal in cross section can be used as long .as they perform both their functions, i. e., permitting an easy ow of gases therebetween and providing support for a relatively thin heating plate 23. Heating plate 23 is annular in shape, andin section is relatively thin so as to easily and quickly transmit heat, lgiven it by the gas ilowing under it, to the bottom portion of the material 24 being treated. To provide rigidity heating plate 23 is fastened to frame 28by bolts 29.

Toprotect the material 24 beingtreated against oxidation I provide a substantially air-tight thin sheet metal hood 25 which is annular in cross section, to completely cover each treating unit. Either -neutral or reducing gas is introduced through pipes 26 and is 'kept in constant circulation by fan 21'. As the gas contacts .the h ot ing treated, it in turn becomes hot and the fan 21 by its motion insures a uniformity of heat throughout the chamber. Bleederpipes 30 are provided as an outlet for the gas after it reaches which is supported by structural members I3.

central portion I4 upon which rests a refractory supporting member I5. Member I5 supports my novel base plate i6 which will hereinafter be more fully described. Furnace Il is provided with a casing I1, refractory walls I8 and a refractory roof I9 to prevent heat losses as is well a predetermined pressure value.

From the foregoing description it will be easily understood that the gas upon'entering the space defined by the hood 25, will be heated, and, by means of the fan 21, will be circulated around the enclosure. It will ow under heating plate 23 between the upstanding lugs 22 of the base plate i6. The heating plate' 23, due to its thinness of section, will quickly transmit the heat contained by thegas to the bottom portion of the treated material 24 which will then attain a substantially uniform temperature throughout known in the art. Roof I9 is removable and 55 its mass. This will not only result'in a more uniform heating eect on the metal. but because of the faster heating of the bottom portion, will give a faster treating cycle and a resulting increase in production. Another result will be a decrease in gas consumption, which means a decrease in costs. l

While I have shown my invention in but one gform, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various other changes and modifications without departing from the spirit thereof, and I desire. therefore, that only such limitations shall be placed thereupon as are specifically set forth in the appended claims.

Having thus described by/invention, what I claim as new and desire to secure by Letters Patent is:

1. A support for material to be heated in a heat treating furnace, said support comprising a base plate and a relatively thin heating plate disposed in spaced relationi'thereto to provide a heat circulating chamber, anjd a plurality of spaced diamond shaped lugs disposed in said chamber and supporting said heating plate.

2. A support for material to be heated in -a heat treating furnace, said support comprising a base plate and arelatively thin heating plate, said base plate comprising a plurality of wedgeshaped members and a plurality of lugs disposed in spaced relation to each other and supporting the heating plate.

3. A base for an annealing furnace comprising a plurality of wedge-shaped lower plates having upstanding spaced diamond-shaped lugs, and an annular relatively thin` heating plate resting on the said lugs of said lower plates.

4. A base for an annealing furnace comprising a lower plate and a relatively thin heating plate disposed in spaced .relation thereto, lugs intermediate said base plate and said heating plate, each of said lugs having sides angularly disposed to'each other and substantially parallel to the sides of adjacent lugs said lugs being disposed in spaced relation to each other to dene a plurality of intersecting passages intermediate the lower plate and the heating plate for the circulation of heat.

. ANDREW J. FISHER. 

